Rails 5.1.5 upgrade causes - uninitialized constant Mime::JSON

Question

Whenever a controller renders json I get, uninitialized constant Mime::JSON I have not modified any code related to this.

Ex, the code for this controller method that throws the error:

def names @families = Family.pluck(:name) render json: @families end

This was working fine before the rails 5 upgrade.

I think the issue is using the responders gem. I had to use the normal respond_to do |format|, syntx in order for it to render correctly. — Chris Habgood, Mar 26 '18 at 20:51

score 3 · Answer 1 · answered May 30 '18 at 12:01

3

In my case, it was jbuilder causing this error.

Upgrading jbuilder to latest (2.7.0 at time of writing) solved this. The old jbuilder references JSON wrong and causes responder to fail.

answered May 30 '18 at 12:01

berkes

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score 2 · Answer 2 · answered Mar 14 '21 at 15:36

2

I was obtaining the error after upgrade from rails 5.0.1 to 5.1.0 and in my case the gem 'web-console','~> 2.0' was causing the error, I solved it updating it to gem 'web-console','>= 3.3.0'.

answered Mar 14 '21 at 15:36

FonchoRG

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Rails 5.1.5 upgrade causes - uninitialized constant Mime::JSON

2 Answers2